The invention relates to prosthetic devices for amputees, and in particular relates to an elastic knit sleeve for use in conjunction with a conventional prosthetic device.
Amputees who have suffered the loss of a limb, and particularly loss of a leg or portion thereof, benefit from a wide assortment of prosthetic devices. Conventional prosthetic devices provide enhanced mobility and include a variety of artificial legs that are secured to the remaining (i.e., residual) portion of a limb. In most circumstances, the length of an amputee""s residual limb determines the type of prosthetic device suitable for the amputee. For example, an amputee having a residual limb extending below the knee may require a partial leg prosthesis (commonly referred to as a xe2x80x9ctranstibialxe2x80x9d). In contrast, an amputee who has suffered the loss of at least a portion of his leg above the knee may require a full leg prosthesis (commonly referred to as a xe2x80x9ctransfemoralxe2x80x9d).
Conventional means for securing a prosthesis to a residual limb (e.g., leg) include a flexible prosthetic sleeve having a locking pin secured to the distal (i.e., lower) end thereof that is rolled on or slipped over the residual limb. It will be understood that the term locking pin refers to an elongate bolt or rod that is suitable for securing a prosthesis to a prosthetic sleeve. In general, prosthetic sleeves that include a locking pin at the distal end are typically manufactured from silicone, thus providing a flexible and durable sheath, and commonly referred to as a xe2x80x9cgel sleeve.xe2x80x9d The gel sleeve and locking pin serve as a foundational point of attachment for a prosthesis to the residual limb.
Typical means for securing a prosthesis to a residual limb further includes a formfitting sleeve, usually knit, having an opening at the distal end that is slipped over the gel sleeve and locking pin. The knit sleeve provides a protective layer between the gel sleeve and the prosthesis. Further, the knit sleeve provides some rotational movement of the residual limb with respect to the prosthesis, thus promoting a natural gate in the amputee""s stride. In other words, the knit sleeve material permits the limb covered by the gel sleeve to shift or slide when the amputee bends the limb-prosthesis combination when walking. The opening at the distal end of the knit sleeve provides a passageway through which the locking pin passes when the knit sleeve is pulled over the gel sleeve.
A conventional prosthesis further includes a form-fitting rigid fiberglass or plastic socket for supporting the residual limb. The socket is shaped to slideably receive a lower portion of the residual limb, thereby sandwiching the gel sleeve and knit sleeve between the residual limb and socket. The socket includes a cylindrical bore extending through a medial portion therethrough for receiving the locking pin when the socket is placed over the residual limb. The socket also provides a rigid framework for attaching a distal attachment device, intermediate coupling components, pylon, and a prosthetic foot.
The distal attachment device connects the socket and sleeve combination to the pylon or artificial leg by means of a conventional locking mechanism. The conventional locking mechanisms referenced herein may include threads and thread stops for engaging a corresponding pin or bolt. The locking mechanism may also include a positive lock and push button release system for locking the pin in place once it is engaged by the prosthesis. Accordingly, the locking pin extending from the distal end of the gel sleeve protrudes through the openings in the distal end of the gel sleeve and continues into the bore in the socket. Further, intermediate coupling components for securing the residual limb, covered by the gel sleeve and knit sleeve, to a prosthesis are secured therebetween by means of conventional locking mechanisms. Finally, the prosthetic foot is attached to the distal end of the prosthesis by any number of conventional locking mechanisms.
The knit sleeve has traditionally been used to provide an additional protective layer between the gel sleeve covering the residual limb and the prosthesis. An amputee may vary the number of knit sleeves depending on the size of the socket relative to the residual limb. Stated differently, an amputee may require multiple knit sleeves of varying thickness to provide a snug, secure fit between the residual limb and the socket of the prosthesis.
Conventional sockets for supporting a residual limb covered by a gel sleeve and knit sleeve and for securing an artificial leg thereto are commonly manufactured from a carbon fiber fabric and acrylic modified epoxy resin for maximum strength and minimum weight. The sockets may also be manufactured from nylon and glass fabric and polyester modified epoxy resin. As referenced above, the gel sleeves that are rolled on over the residual limb are typically made of pliable silicone. The knit sleeve provides some lateral movement of the gel sleeve relative to the socket, thereby promoting greater flexibility and increased range of motion of the artificial leg. Absent the knit sleeve, the silicone-on-epoxy resin interface between the gel sleeve and socket would result in a stiff and inflexible movement of the amputee""s leg during a normal stride. The knit sleeve covering the gel sleeve also reduces frictional forces caused by the surfaces of the gel sleeve and socket in contact with one another, thus minimizing the wear on the surfaces of the prosthesis.
The normal xe2x80x9cwear and tearxe2x80x9d on the interior and exterior surfaces of the knit sleeve in contact with the gel sleeve and socket results in the degradation and eventual breakdown of the yarns forming the knit sleeve. This breakdown or xe2x80x9cunravelingxe2x80x9d of yarns comprising the sleeve is especially prevalent at the distal end portion of the knit sleeve. The distal end portion of the knit sleeve is in constant contact with the interior of the socket and, therefore, is subject to increased friction due to the rotational and lateral movement of the sleeve-covered residual limb against the interior of the socket. During the ambulatory movement of the amputee, these frictional forces result in xe2x80x9chot spotsxe2x80x9d at the distal end portion of the knit sleeve which tend to degrade the structure of the individual yarns forming the sleeve and eventually leads to the unraveling of the yarns. Therefore, the distal end of the knit sleeve tends to xe2x80x9cwear outxe2x80x9d before the remainder of the sleeve.
An elliptical slit at the distal end of typical knit sleeves for receiving a locking pin fails to provide continuous contact between the perimeter of the slit and the peripheral contour of the locking pin. The lack of continual contact around the perimeter of the elliptical slit causes the knit material forming the distal end of conventional knit sleeves to overlap and bunch during use of the prosthesis. The overlapped and bunched material contributes to increased friction, which leads to unraveling. Further, the bunching of material at the end of the knit sleeve compounds any discomfort to the amputee caused by the constant pressure of the socket against the end of the residual limb.
Further, typical methods for forming the openings at the distal end of most knit sleeves include burning or cutting the sleeve material. This technique, however, results in frayed yarn ends defining the perimeter of these conventional openings. If the perimeter lacks sufficient reinforcement, the yarns ends tend to degrade the structural integrity of the opening and thereby promote rips or xe2x80x9crunsxe2x80x9d that progressively extend the length of the distal end of the sleeve. The tattered knitting of the knit sleeve material accumulates between the gel sleeve and socket, thus leading to the bunching of material at the distal end of the knit sleeve.
Conventional techniques for reducing movement of a residual limb relative to a prosthesis include U.S. Pat. No. 5,728,1672 Lohman which discloses a prosthetic sock with vertical strips or patches disposed on an inner and outer surface thereof. The outer surfaces of the patches are rough to prevent the sock from slipping. Lohman includes an opening at the distal end of the sock surrounded by patches placed on the interior and exterior of the sleeve. Nevertheless, the patch surrounding the opening fails to sufficiently reinforce the yarns at the distal end of the sleeve. Thus, the yarns tend to unravel after prolonged use of the knit sleeve.
The conventional knit sleeves described above fail to address the need for a reinforced circular opening at the distal end of the sleeve for receiving the locking pin. Therefore, there is a need for a prosthetic sleeve that prevents the bunching of material at the distal end of the sleeve.
Further, there is a need for a prosthetic sleeve having reinforced yarn at the distal end to avoid discomfort and excessive wear due to the bunching.
There is an additional need for a prosthetic sleeve having a reinforced circular opening at the lower end of the sleeve to avoid the unraveling of the yarn ends forming the opening.
Accordingly, it is an object of the invention to provide a prosthetic sleeve having a defined circular opening at the distal end for receiving a locking pin affixed to an end of a gel sleeve.
It is a further object of the present invention to provide a circular opening having a reinforced perimeter for preventing the unraveling of yarns subject to the frictional forces created between the contact surfaces of the gel sleeve and socket.
It is yet a further object of the invention to provide a prosthetic sleeve having a layer of gel for coating a reinforced perimeter of the circular opening for further preventing the unraveling of the yarn.
It is yet another object to provide a prosthetic sleeve having a layer of gel covering a portion of the interior and exterior of the distal end of the sleeve immediately surrounding the circular opening for providing an additional boundary layer and for preventing the breakdown of the sleeve material at the distal end portion of the sleeve immediately surrounding the circular opening.
The invention meets these objects with an improved fabric or knit sleeve for covering a gel sleeve that includes a reinforced circular opening at the distal end of the sleeve that is sewn or serged and then optionally coated with a gel to prevent unraveling of the yarn. The sleeve is typically knit because of the beneficial elastic or xe2x80x9cform-fittingxe2x80x9d qualities knitting provides to articles worn on the body. Nevertheless, the present invention is not limited to a knit sleeve. The circular or round openingxe2x80x94as opposed to an elliptical slit-insures a conforming fit of the circular opening around the nipple or ledge at the base of the locking pin where the pin protrudes from the gel sleeve, thus reducing the likelihood of the sleeve material to bunch in areas between the gel sleeve and socket.
In practice, an amputee first pulls the gel sleeve having a locking pin attached thereto at a distal end over the residual limb, aligns the circular opening of the improved knit sleeve with the distal end of the locking pin, and then slips the knit sleeve over the gel sleeve and locking pin. Next, the amputee positions the residual limb covered by the knit sleeve and gel sleeve into the interior of the rigid socket. The socket is affixed to the residual limb by means of a conventional distal attachment device (e.g., cylindrical plate). In other words, the locking pin passes through an opening in the socket and engages a locking mechanism in an upper portion of the distal attachment device. Next, the amputee connects a lower portion of the distal attachment device to one end of a pylon with intermediate coupling components. Thereafter, the amputee secures a prosthetic foot to an opposite end of the pylon.
The reinforced circular opening at the distal end of the knit sleeve has the advantages of providing a snug fit around the periphery of the base of the locking pin (i.e., nipple) thereby minimizing the unraveling of yarns at the distal end of the sleeve and preventing accumulation of knit material between the gel sleeve and socket. Moreover, the polymer coating on the serged yarns hinders premature breakdown of the knit sleeve.
In sum, the advantages of the present invention mentioned above enhance the durability of the distal end of the knit sleeve and prevents bunching of the knit sleeve between the gel sleeve and prosthesis (i.e., socket).
The foregoing and other objects and advantages of the invention and the manner in which the same are accomplished will become clearer based on the following detailed description taken in conjunction with the accompanying drawings in which: